A person who suffers from a major depressive episode must either have a depressed mood or a loss of interest or pleasure in daily activities consistently for at least a 2 week period. This mood must represent a change from the person’s normal mood; social, occupational, educational or other important functioning must also be negatively impaired by the change in mood. A major depressive episode is also characterized by the presence of 5 or more of these symptoms:

Depressed mood most of the day, nearly every day, as indicated by either subjective report (e.g., feeling sad or empty) or observation made by others (e.g., appears tearful). (In children and adolescents, this may be characterized as an irritable mood.)

Markedly diminished interest or pleasure in all, or almost all, activities most of the day, nearly every day

Significant weight loss when not dieting or weight gain (e.g., a change of more than 5% of body weight in a month), or decrease or increase in appetite nearly every day.

Insomnia (inability to sleep) or hypersomnia (sleeping too much) nearly every day

Psychomotor agitation or retardation nearly every day

Fatigue or loss of energy nearly every day

Feelings of worthlessness or excessive or inappropriate guilt nearly every day

Diminished ability to think or concentrate, or indecisiveness, nearly every day

Recurrent thoughts of death (not just fear of dying), recurrent suicidal ideation without a specific plan, or a suicide attempt or a specific plan for committing suicide

A major depressive episode also is generally not diagnosed when the same symptoms could be attributed to Bereavement (normal feelings of sadness after the loss of a loved one).